We are studying a numer of physico-chemical properties of monoamine oxidase (MAO) which we believe to be of major the understanding of the biofunction of this enzyme. Specia attention is being paid to the analysis of some of the forces involved in the interaction between MAO and its substrates and inhibitors. The information thus gained is mainly used to induce in vivo changs of MAO and to observe the metabolic and functional cosequencesof these alterations. This endeavor is part of our continuous attempt to develop experimental systems with MAO acting as an integral part f the regulatory apparatus which establishes and mintains optimal amine levels necessary for neurotransmission rather than being a mere scavenger for some tray amines. Some of the special topics are as follows: (a) Typology of MAO of human and other tissues; (b) Kinetic analysis of the degradation of phyenylethylamine (PEA) and of a series of hydroxylated derivatives by the B-type of MAO; (c) Effect of age and sex on MAO activity and amine levels in amn and animals; (d) Role of PEA in adrenergic systems and in the initiation of aggregation of human platelets; (e) Rol of MAO in the pathogenesis of neurological and psychiatric disorders (Parkinson's disease, schizophrenia, functional dyslexia, glaucoma); (f) Effect of mescaline of metabolism and function of cerebrl dopamine in goldfish; (g) Retinal function in Parkinson's disease. BIBLIOGRAPHIC REFERENCES: E.A. Zeler, P.A. Knepper and D. Shoch, Differential effects of inhibitors of monoamine oxidase types A and B on the adrenrgic system of the rabbit iris, Invest. Ophthalmol. 14, 155-9 (1975). B. Boshes, R.R. Moody, M.J. Kupersmith and E.A. Zeller, The role of monoamines in learning and mrmor consolidation, Internat. J. Neurophysiol. l0, l72-77 (l975).